Landing gear and method of assembly

ABSTRACT

Landing gear for selectively supporting a semitrailer and a method of assembly of the landing gear is provided. The landing gear includes a leg having an upper section and a lower section telescopingly received in the upper section. A lead screw extends and retracts the upper and lower sections relative to each other upon rotation thereof. An input shaft applies a torque to the lead screw to drive rotation thereof, the input shaft being rotatable about a rotation axis and movable in translation along the rotation axis for shifting between a first position for low gear operation and a second position for high gear operation. An output shaft, axially aligned with the input shaft, has an output gear for transmitting torque to the lead screw. A gearing subassembly is received in the upper leg section and is configured to augment lift when the input shaft is in the first position and augment speed in the second position.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/369,502, filed Apr. 2, 2002, titled LANDING GEAR AND METHOD OFASSEMBLY.

BACKGROUND OF THE INVENTION

This invention relates generally to landing gear used in the support ofsemitrailers and more particularly to gearing configurations of alanding gear.

Landing gear of the present invention has particular application in thesupport of semitrailers when they are not attached to a tractor. Thelanding gear conventionally includes a pair of telescoping legs capableof extending to engage the pavement or other supporting surface to holdup the front end of the semitrailer, and of retracting to move up out ofthe way when the semitrailer is being pulled over the road by a tractor.The extension and retraction is most often carried out by the drivermanually turning a crank connected by gearing to a lead screw in theleg. The lead screw interconnects telescoping leg sections of the leg soas to retract a lower leg section into an upper leg section or extendthe lower leg section from the upper leg section depending on thedirection the screw is rotated.

The semitrailers are very large and heavy by themselves, and furthercarry large loads. In order to lift such loads when extending the legs,the gearing provides a mechanical advantage in addition to the crank. Inproviding the mechanical advantage, the rotation of the lead screw isvery much retarded in relation to the rotation of the crank. In otherwords, it will require numerous turns of the crank to achieve a verysmall linear travel of the lower leg section relative to the upper legsection. The high ratio of turns per inch of travel is acceptable whenthe legs are actually bearing the load of the trailer because of theaccompanying mechanical advantage. Once the load is relieved from theleg, such as when the semitrailer is supported by the tractor, the slowlinear movement of the lower leg section becomes an issue because of thelong time it takes to get the lower leg section retracted far enoughabove the ground for safe travel over the road. Likewise, slow extensionof the lower leg section into engagement with the pavement is alsohighly undesirable. It is known to provide for shifting between a lowgear and a high gear in the gearing, with the low gear providing themechanical advantage needed for lifting large loads and high gearproviding for more rapid linear movement of the lower leg section (i.e.,a lower turns per inch ratio). Co-assigned U.S. Pat. No. 4,187,733discloses gearing of this type. Generally, a large difference betweenthe turns per inch ratio in low gear versus high gear is desirable.

One way to assist in providing greater lift in low gear is to provide agear on an idler shaft located between the input shaft (of the crank)and the output shaft connected to the lead screw. This arrangement istypically referred to as a double reduction. An idler shaft requiresadditional space in the gear box, which is at a premium. In addition,there are two additional openings in the gear box containing bearingsfor the idler shaft. These openings provide an additional place fromwhich leakage of lubricant becomes more likely over the life of thelanding gear.

Conventionally, the gearing has been located in a gear box which isformed separately from the leg. For instance, the gear box may be formedfrom two halves which are individually stamped and later boltedtogether. The gears making up the gearing may be installed in one halfof the gear box before it is completed. The gear box is welded orotherwise attached to the landing gear leg on the inside or outside ofthe leg. The input shaft from the crank, and the output shaft which isconnected to the lead screw, are held by bearings located in the landinggear leg. The conventional construction requires a number of parts inaddition to the landing gear leg and several manufacturing steps toassemble the gearing in the gear box with the input and output shaftsand the leg. It is known to incorporate some of the gearing in the leg,but significant manufacturing steps are required to assemble componentparts of the gearing together with the input and output shafts.

SUMMARY OF THE INVENTION

Among the several objects and features of the present invention may benoted the provision of landing gear which is of simplified construction;the provision of such landing gear having a compact gear arrangement;the provision of such landing gear which provides additional torque inlow gear and augmentation of crank rotation in high gear to increasespeed; the provision of such a landing gear which inhibits leakage oflubricant; the provision of such landing gear which has fewer externalbearings receiving shafts; the provision of such landing gear which hasfewer parts; the provision of such landing gear which is lighter inweight; and the provision of such landing gear which can be efficientlyassembled.

Further among the several objects and features of the present inventionmay be noted the provision of a method of assembling landing gear whichcan be carried out rapidly and with precision; the provision of such amethod which reduces the number of externally exposed shaft bearings tominimize leakage; and the provision of such a method which reduces thenumber of steps to complete manufacture of the landing gear.

In general, one embodiment of the invention is directed to landing gearfor selectively supporting a semitrailer. The landing gear includes aleg having an upper section and a lower section in telescopingarrangement with each other and a lead screw mounted for extending andretracting the upper and lower sections relative to each other uponrotation of the lead screw. The landing gear also includes an inputshaft for applying a torque to the lead screw to drive rotation thereof,the input shaft being rotatable about a first rotation axis and movablein translation along the first rotation axis for shifting between afirst position for low gear operation and a second position for highgear operation. The landing gear also includes an output shaft includingan output gear for transmitting torque to the lead screw, the outputshaft being mounted for rotation about a second rotation axis and beinggenerally axially aligned with the input shaft. The landing gear alsoincludes a gearing subassembly configured so that for each rotation ofthe input shaft, the output shaft rotates less than one rotation for lowgear operation and interconnecting the generally axially aligned inputand output shafts in the second position so that for each rotation ofthe input shaft, the output shaft rotates more than one rotation,whereby the gearing subassembly augments lift when the input shaft is inthe first position and augments speed in the second position.

The invention is also directed to landing gear for selectivelysupporting a semitrailer. The landing gear includes a leg having anupper section and a lower section in telescoping arrangement with eachother and a lead screw mounted for extending and retracting the upperand lower sections relative to each other upon rotation of the leadscrew. The landing gear also includes an input shaft rotatable about afirst rotation axis and an output shaft rotatable about a secondrotation axis and connected for driving rotation of the lead screw. Thelanding gear further includes an idler shaft rotatable about a thirdrotation axis and gearing associated with the input shaft, output shaft,idler gear and lead screw for operatively connecting input shaft to thelead screw for driving rotation thereof. The landing gear also includesa bearing member located within the upper section of the leg andincluding a bearing element bearing the idler shaft for rotation, thebearing member being supported by the upper section at a location abovethe location of the bearing element.

Another embodiment of the invention is directed to landing gear forselectively supporting a semitrailer. The landing gear includes a leghaving an upper section and a lower section in telescoping arrangementwith each other and a lead screw mounted for extending and retractingthe upper and lower sections relative to each other upon rotation of thelead screw. The landing gear also includes an input shaft rotatableabout a first rotation axis and movable in translation along the firstrotation axis for shifting between a first position for low gearoperation and a second position for high gear operation and an outputshaft mounted for rotation about a second rotation axis. The landinggear further includes a first idler shaft mounted for rotation about afirst idler shaft axis spaced from the axis of rotation of the inputshaft and a second idler shaft mounted for rotation about a second idlershaft axis spaced from the axis of rotation of the input shaft. Theinput shaft and the first idler shaft are arranged such that in thefirst position torque from the input shaft is transmitted through thefirst idler shaft to the lead screw and the output shaft and the inputshaft and the second idler shaft are arranged such that in the secondposition torque from the input shaft is transmitted through the secondidler shaft to the output shaft and lead screw.

Another embodiment of the invention is directed to landing gear forselectively supporting a semitrailer. The landing gear includes a leghaving an upper section and a lower section in telescoping arrangementwith each other. The upper section has opposing walls, a first of thewalls having a slot therein at an upper end. The landing gear alsoincludes a lead screw mounted for extending and retracting the upper andlower sections relative to each other upon rotation of the lead screwand an input shaft rotatable about a first rotation axis and connectedin operation to the lead screw for driving rotation thereof. The inputshaft extends into the upper section of the leg through the slot in thefirst wall. The landing gear further includes a cover plate attached tothe upper section generally over the slot, the cover plate including abearing receiving the input shaft there through.

Another embodiment of the invention is directed to a method ofassembling a landing gear leg. The method includes the steps of mountingat least one shaft on a bearing located in a bearing member andinserting the bearing member mounting the shaft into an upper section ofthe landing gear leg.

Another embodiment of the invention is directed to a subassembly for usein manufacturing a landing gear leg. The subassembly includes a bearingmember adapted to be mounted on the leg in an open top thereof and ashaft mounted on the bearing member for rotation. The subassembly alsoincludes gearing associated with the shaft for use in transmittingrotation, whereby the shaft and gearing are supported for rotationindependently of mounting in the leg.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation of a semitrailer unhitched from its trucktractor, and having landing gear thereon supporting the front end of thesemitrailer;

FIG. 2 is an enlarged perspective view of a landing gear leg of thelanding gear depicted in FIG. 1;

FIG. 3 is a front side elevation of the landing gear leg of FIG. 2;

FIG. 4 is a right side elevation of the landing gear leg of FIG. 2;

FIG. 5 is an exploded perspective view of the landing gear leg of FIG. 2capable of receiving a gearing subassembly for both conventional andreverse mounted legs;

FIG. 6 is a side elevation of a mounting plate of the landing gear legof FIG. 2;

FIG. 7 is a side elevation of an upper portion of the landing gear leg;

FIG. 8 is a plan view of an upper section of the landing gear leg;

FIG. 9 is a bottom side perspective of a top cover and associated idlershaft and gearing of a single idler landing gear leg according to oneembodiment of the invention;

FIG. 10 is an inverted view of the top cover and idler shaft of FIG. 9with the parts exploded to illustrate assembly;

FIG. 11 is a schematic fragmentary cross section of the single idlerlanding gear leg of FIG. 9 with the input shaft in the low gearposition;

FIG. 12 is a schematic fragmentary cross section of the single idlerlanding gear leg of FIG. 9 with the input shaft in the high gearposition;

FIG. 13A is an end view of the idler shaft of the single idler landinggear of FIG. 9;

FIG. 13B is a sectional view of the idler shaft taken along line 13B—13Bof FIG. 13A;

FIG. 14 is a bottom side perspective of a top cover of the single idlerlanding gear leg;

FIG. 15 is an inverted perspective view of the top cover of FIG. 14 withthe parts exploded to illustrate assembly;

FIG. 16 is a schematic, fragmentary cross section of another version ofthe single idler landing gear leg having an idler shaft supported fromthe side internally of the leg;

FIG. 17 is a bottom side perspective of a top cover and associated dualidler shafts and gearing according to one embodiment of the invention;

FIG. 18 is an inverted perspective view of the top cover and dual idlershafts of FIG. 17 with the parts exploded to illustrate assembly;

FIG. 19 is a schematic, fragmentary side elevation of a dual idlerlanding gear leg with a wall of the leg and other selected parts brokenaway to reveal construction with the input shaft in the high gearposition;

FIG. 20 is a schematic, fragmentary side elevation of a dual idlerlanding gear leg with a wall of the leg and other selected parts brokenaway to reveal construction with the input shaft in the low gearposition;

FIG. 21 is an enlarged fragmentary side elevation of the dual idlerlanding gear;

FIG. 22A is an end view of the low idler shaft of the dual idler landinggear;

FIG. 22B is a sectional view of the low idler shaft taken along line22B—22B of FIG. 22A;

FIG. 23A is an end view of the high idler shaft of the dual idlerlanding gear;

FIG. 23B is a sectional view of the high idler shaft taken along line23B—23B of FIG. 23A;

FIG. 24 is a bottom side perspective of the top cover of the dual idlerlanding gear leg;

FIG. 25 is an exploded perspective of the top cover of FIG. 24;

FIG. 26 is a fragmentary front elevation of a single idler landing gearleg having components substantially identical to the dual idler landinggear leg of FIGS. 20 and 21; and

FIG. 27 is a fragmentary side elevation of the single idler landing gearleg with a wall of the leg and other selected parts broken away toreveal construction.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates landing gear, indicated generally at 10, for thesupport of semitrailers when not attached to a tractor. The landing gear10 typically includes a pair of legs 11 (only one leg is shown) locatednear respective front corners of a semitrailer 12. Each leg 11 iscapable of extending to engage the pavement S or other supportingsurface to hold up the front end of the semitrailer as is wellunderstood in the art. A shoe 14 of the landing gear 10 is pivotallymounted on the leg 11 for engaging the pavement S. The legs 11 are alsocapable of retracting to move up out of the way when the semitrailer 12is being pulled over the road by a tractor (not shown). A crank handle16 is used to extend and contract the length of the leg 1, as will bedescribed below. The following description is confined to one of thelegs 11. The other leg (not shown) has a similar construction, but if itis connected to gearing of the illustrated leg such as by an outputshaft extending underneath the front of the semitrailer 12, the otherleg need not have some of the gearing present in the illustrated leg.Such constructions are well understood by those of ordinary skill in theart and will not be further described herein.

Referring to FIGS. 2–5, the landing gear leg 11 includes a lower legsection 13 (FIG. 5) telescopingly received in an upper leg section 15.The lower leg section 13 is a steel square tube. The upper leg section15 is preferably a square tube made of steel or other like material. Theupper leg section 15 has internal dimensions larger than that of thelower leg section 13 so that the lower leg section is telescopinglyreceived in the upper leg section.

The lower and upper leg sections 13, 15 could also have other crosssectional shapes, such as rectangular, round or the like. In analternate version, the upper leg section is a steel channel having anopen front side extending the length of the upper leg section. Amounting plate 17 for attaching the leg 11 to the trailer 12 is attachedby bolts and/or welding to the upper leg section 15. Holes 17A in themounting plate 17 may receive fasteners (not shown) for attaching theleg 11 to the trailer 12. The leg 11 can be attached to the trailer ineither a “conventional mount” and “reverse mount”. These labels will beunderstood by those of ordinary skill in the art and will not bediscussed further.

FIG. 5 illustrates that the upper leg section 15 has two U-shapedcutouts 18, 20 extending axially downward from the upper end of theupper leg section on opposite sides of the upper leg section. In thefinal assembly, the cutouts 18 and 20 are closed by an outside coverplate 19 and an inside cover plate 21, respectively. For illustrativepurposes, with the conventionally mounted leg 11, the “outside” coverplate 19 faces out to the side of the semitrailer and the “inside”coverplate 21 faces in toward the center of the semitrailer. The upperleg section 15 is formed with two pockets 22 extending outward from theupper leg section on opposite sides of the upper leg section. Thepockets 22 are formed on the sides of the upper leg section that do nothave the cutouts 18, 20. The pockets 22 are sized to accommodate anidler gear as will be described below.

The lower and upper leg sections 13, 15 are connected together by a leadscrew 23 (only the very upper portion of which is illustrated in FIG. 5)for extension and retraction of the lower leg section 13 relative to theupper leg section 15 upon rotation of the lead screw. The lead screw 23has a bevel gear 25 mounted on its upper end for use in driving the leadscrew as will be described. The landing gear leg 11 includes an inputshaft 27 received through the outside cover plate 19 into the leg and anoutput shaft 31 received through the inside cover plate 21 of the leg.The input shaft 27 and output shaft 31 are connected together asubassembly 32 further including gearing as will be described below.More specifically, the gearing subassembly 32 is preferably constructedand arranged to fit substantially within the cross sectional area of theupper leg section 15. In one embodiment, the output shaft 31 wouldextend to the aforementioned other leg (not shown) of the landing gearto drive the rotation of the lead screw in that leg. The crank handle 16(FIG. 1) is preferably attached to the outer end of the input shaft 27for manually applying torque to rotate the input shaft.

Assembly of the landing gear leg 11 may performed by dropping the topcover 47 and associated components of the subassembly 32 onto the opentop of the upper leg section 15. Thus, in one preferred embodiment, thegearing components of the subassembly, such as the idler shafts, theoutput gear, the pinion gear and the large diameter input gear, as willbe described below, are all received within the upper leg section 15.The input shaft 27 passes through the cutout 18 on the outside of theupper leg section 15 and the output shaft 31 passes through the cutout20 on the inside of the upper leg section. Cover plate bolts extendthrough holes in respective cover plates 19, 21 and into the top cover47 to secure the subassembly 32 to the leg 11. The cover plates 19, 21may also be welded to the upper section 15 and/or a gasket (not shown)maybe provided between the cover plate (19, 21) and upper section.

Preferably, the leg 11 is constructed selectively for eitherconventional mounting on a semitrailer or reverse mounting by turningthe subassembly 32 to the upper section 15 through 180 degrees. Nothingelse about the construction of the leg changes, which simplifiesmanufacturing. It maybe seen that the upper end of the upper leg section15 has the opposite laterally outwardly formed pockets 22. In addition,the front side of the upper leg section 15 has an outwardly formedportion 24. The pockets 22 provide space for the gears of the idlershafts (not shown) without regard to the orientation of the subassembly32. The outwardly formed portion 24 keeps the distance from a center ofthe upper section 15 to the respective cutouts 18, 20 equal. Thus, abeveled pinion gear member (described below with reference to FIG. 9) inthe subassembly 32 will mesh with the bevel gear 25 at the top of thelead screw 23 no matter which direction the top cover subassembly isoriented. FIG. 5 shows the top cover subassembly 32 oriented for bothconventional mount and for reverse mount. In either orientation, thesubassembly 32 can be dropped into the open top of the upper leg section15 for assembling the leg 11.

FIG. 6 illustrates a mounting plate 17′ used with an upper leg portion(not shown) shaped as a channel and is configured to cover the openfront side of the upper leg portion. FIGS. 7 and 8 illustrate a modifiedversion of an upper section 15″ of a landing gear leg having the shapeof a square tube. The upper section 15″ has a mounting plate 17″attached thereto. The upper end of the upper section 15″ is belledoutwardly to form pockets 22″ and outwardly formed portions 24″. Thepockets 22″ and outwardly formed portions 24″ extend over a substantialportion of the width of their respective side walls. Otherwise, theconstruction of the upper section 15″ is substantially the same as uppersection 15. The upper leg section 15 at its upper end is symmetricalabout a central plane P.

FIGS. 9–16 illustrate a subassembly, generally designated at 32, andparts thereof separately and in combination with the leg 11. Referringto FIGS. 9 and 10, the subassembly 32 comprises a single idler shaft 45(FIG. 13) for mechanically connecting the input shaft 27 with the outputshaft 31. The input shaft 27 is received through a bearing 29 in theoutside cover plate 19 into the leg 11 and the output shaft 31 isreceived through a bearing 33 in the inside cover plate 21 of the leg.The top cover 47 has been removed from FIG. 9 for clarity.

The inner end of the input shaft 27 has a reduced diameter and isreceived and borne in an axial opening of an output gear 35 of theoutput shaft 31 for free rotation relative to the output gear and foraxial movement relative to the output gear. Alternately, the outputshaft has a reduced diameter end portion (not shown) which is receivedin an axial opening in the input shaft, or the shafts could be supportedindependently of each other. Thus, the input and output shafts 27, 31are coaxal. The bearing 29 supporting the input shaft 27 in the outsidecover plate 19 permits the input shaft to both rotate and move axiallyrelative to the bearing. As to axial movement, a ball and springmechanism (not shown) is provided to engage the bearing 29 to releasablylock the input shaft 27 in two axial positions, corresponding to lowgear (FIG. 11) and high gear (FIG. 12), respectively.

The input shaft 27 carries a pinion gear 37 which is pinned to thereduced diameter portion of the input shaft for conjoint rotation withthe input shaft. It is contemplated that the pinion gear 37 could beformed as one piece with the input shaft 27. The pinion gear 37 has asmall diameter, and has a first set of gear teeth 38 and a second set ofgear teeth 40. The input shaft 27 also mounts a large diameter inputgear 39 for free rotation relative to the input shaft, except as will bedescribed, but which is held from movement along the axis of the inputshaft relative to the upper leg section 15. A central, internallytoothed opening 42 of the input gear 39 has a diameter which is largerthan the input shaft 27 for receiving a part of the pinion gear 37 intothe central opening. The large diameter input gear 39 includes a flatcentral portion 46 and an angled outer portion 48. This constructionpermits the large diameter gear 39 to fit closely against the outsidecover plate 19 and between the outside cover plate and the bevel gear 25of the lead screw 23. The annular outer portion 48 of the large diametergear 39 angles outwardly and has teeth formed therein for meshing withanother gear as will be described.

The output gear 35 is pinned to the output shaft 31 for conjointrotation. The output gear 35 includes first gear member 41 whichreceives input torque to drive the gear and a second beveled pinion gearmember 43 which is meshed with the bevel gear 25 of the lead screw 23.The first gear member 41 is substantially planar and fits close againstthe inside cover plate 21 and between the bevel gear 25 and the coverplate. As illustrated, the output gear 35 is formed as a single piece oftubular material. However, it may be formed from multiple pieces whichare separated and secured to a common tube, or directly to the outputshaft 31.

Driving connection of the input shaft 27 with the output gear 35 isachieved by way of an idler shaft 45 having three idler gears formed asone piece with the shaft. It would be possible to form the gearsseparately from the shaft and connect them to the shaft. As shown inFIGS. 11 and 12, the idler shaft 45 is supported for rotation within theupper leg section 15 by a top cover 47. In certain statements of thepresent invention, the top cover 47 may be considered to be a “bearingmember”. The top cover will be described more fully hereinafter. A firstidler gear 49 has the smallest diameter of the gears on the idler shaftand is permanently meshed with the large diameter input gear 39. Asecond idler gear 51 has the largest diameter and is located generallyin the middle of the idler shaft 45 for selective engagement with theteeth 40 of the pinion gear 37 of the input shaft 27. A third idler gear53 located at the far left end of the idler shaft 45 has a diameterbetween that of the first and second idler gears and is permanentlymeshed with the first gear member 41 of the output gear 35.

Referring to FIGS. 14 and 15, a top cover 47 of the single idler landinggear leg 11 is formed to rotatably mount the idler shaft 45. Preferably,it is not necessary to have additional openings in the exterior of theleg 11 through which rotating shafts are received, which are primelocations for leaking lubricant. The top cover 47 is made eitherpartially or entirely of a polymeric material such as nylon. However, itis contemplated that the top cover 47 may be made of other suitablematerials, such as a ductile iron casting or aluminum casting, withoutdeparting from the scope of the present invention. It is believed noseparate bearings will be necessary if the top cover 47 is made of nylonor a like material. In one version, side flange 70 of the top cover 47has openings 72 therein for receiving bolts or screws to secure thecover plate 19 (see FIG. 10) to the top cover. The top cover has a firstoutwardly formed pocket 74 extending from a top surface 75 thereof. Thepocket 74 provides space for receiving the second idler gear 51 (seeFIG. 10). The top cover 47 also has a second outwardly formed pocket 76extending from the top surface 75 for receiving the third idler gear 53.Side flange 78 of the top cover 47 has openings (not shown) therein forreceiving bolts or screws to secure the cover plate 21 (see FIG. 10) tothe top cover.

Referring now to FIG. 15, the top cover 47 includes a first yoke 81which receives a section of the idler shaft 45 between the first idlergear 49 and the second idler gear 51, and a second yoke 83 whichreceives a section of the idler shaft between the second idler gear andthe third idler gear 53. The first and second yokes 81, 83 each have alower portion 81A, 83A which can be separated from an upper portion 81B,83B to place the idler shaft 45 in the top cover 47. Bolts 84 may beused to connect the lower portions 81A, 83A to respective upper portions81B, 83B. The gearing subassembly 32, top cover 47, outside cover plate19, inside cover plate 21, input shaft 27, and output shaft 31 may besubassembled and dropped into the upper leg section 15 as shown in FIG.5.

Referring again to FIGS. 11 and 12, the operation of the landing gear isas follows. Assuming the lower leg section 13 (FIG. 2) is retracted intothe upper leg section 15 and is to be extended, the driver first movesthe input shaft 27 axially outwardly to the position shown in FIG. 12.In this position, the pinion gear 37 is partially received in thecentral opening 42 of the large diameter input gear 39. The use of asmall pinion gear 37 is adopted from co-assigned U.S. Pat. No.4,187,733, the disclosure of which is incorporated by reference. Thefirst set of teeth 38 on the right side of the pinion gear 37 mesh withthe internal teeth of the large diameter gear 39 so that the largediameter gear is now fixed for conjoint rotation with the input shaft27. Thus, the engagement of the large diameter gear 39 with the firstidler gear 49 is a driving engagement. As is understood by those ofordinary skill in the art, the idler shaft 45 will be rotated morerapidly than the input shaft 27. The torque is transmitted by the idlershaft 45 to the third gear 53 meshed with the first gear member 41 ofthe output gear 35 for driving the output gear at a rotational ratewhich is greater than that of the input shaft 27. For example and not byway of limitation, if the ratio of teeth of the larger diameter gear 39to that of the first idler gear 49 is 31T/7T and the ratio of teeth onthe second idler gear 53 to the first output gear member 41 is 13T/25T,the output shaft rotates 2.3 times faster than the input shaft. Theratio of the turns of the crank handle 16 (see FIG. 1) per inch oftravel of the lower leg section 13 for this version is 1.97. In thisway, the lower leg section 13 can be more rapidly extended from theupper leg section 15 for bringing the leg into contact with the pavementS.

Once the leg 11 contacts the pavement, it will be necessary to increasethe mechanical advantage provided by the gearing to lift the semitrailer12 (FIG. 1) off of the fifth wheel of the tractor (not shown). To dothis, the driver moves the input shaft 27 axially inwardly so that thepinion gear 37 moves out of the central opening 42 of the large diameterinput gear 39 and into engagement with the teeth of the second idlergear 51 (as shown in FIG. 11). The large diameter input gear 39,although still meshed with the first gear 49 of the idler shaft 45 doesnot transmit any torque from the input shaft 27 and does not rotateconjointly with the input shaft. The second set of teeth 40 on the leftside of the pinion gear 37 mesh with the teeth of the second idler gear51. It will be readily apparent that rotation of the input shaft 27 willbe substantially reduced by the second idler gear 51, producing anaccompanying increase in torque. The higher torque is transmitted by thethird idler gear 53 to the first gear member 41 of the output gear 35,achieving a further (or “double”) reduction. Now rotation of the inputshaft 27 produces extension of the lower leg section 13 at a slowerrate, but with greater lift to raise the semitrailer 12 and its load.

FIG. 16 illustrates another version of the single idler landing gear leg111, where corresponding parts are indicated by the same referencenumeral, but with the prefix “1”. An idler shaft 145 is supported bybushings associated with outside and inside cover plates 119, 121 ratherthan being supported by the top cover. In this embodiment, the top cover147 is not used to support the idler shaft 145. Otherwise, theconstruction is substantially identical to FIG. 9 and will not befurther described herein. Referring again to FIG. 16, it may be seenthat the idler shaft 145 has a reduced diameter stub 185 at the rightend thereof and an enlarged diameter portion 187 at its left end. Thestub 185 is journaled in a bushing 189 which is fitted into an openingformed in the outside cover plate 121 for rotation of the idler shaft145. The bushing 189 blocks the opening to assist in sealing the leg 11.A short axle 191 is received through an opening in the inside coverplate 121 and into a recess in the enlarged diameter portion 187 of theidler shaft to mount the idler shaft 145 for rotation. The axle 191 issealably secured to the inside cover plate 121, such as by welding. Thefitted bushing 189 and the short axle 191 mount the idler shaft 145 forrotation between the outside and inside cover plates 119, 121. Thus,there is no moving part extending through the outside and inside coverplates 119, 121. Thus, although the idler shaft 145 is supported fromthe sides of the leg 11, it does not extend through the sides.Accordingly, a prime site for the leakage of lubricant (through arotating shaft bearing) is eliminated.

Some examples of possible high gear and low gear ratios for the singleidler leg 11 are listed below in turns of the crank handle 16 per inchof travel of the leg.

Low Gear - 29.2 Low Gear - 32.8 Low Gear - 35.1 High Gear - 1.8 HighGear - 1.97 High Gear - 3.3 Low Gear - 38 Low Gear - 41.8 Low Gear -35.1 High Gear - 1.8 High Gear - 1.97 High Gear - 4.5 Low Gear - 35.1High Gear - 3.9

FIGS. 17–25 collectively show a landing gear leg 211 and componentsthereof, of another embodiment. Corresponding parts are indicated by thesame reference numeral as for the landing gear leg 11, but with theprefix “2”. FIGS. 17 and 18 illustrate a gearing subassembly 232 and atop cover 247 of the dual idler shaft landing gear leg 211. Thesubassembly comprises a dedicated low gear idler shaft 257 (FIGS. 22Aand 22B) and a separate, dedicated high gear idler shaft 263 (FIGS. 23Aand 23B) for mechanically connecting an input shaft 227 with an outputshaft 231. The input shaft 227 is received through a bearing 229 in anoutside cover plate 219 into the leg 211 and the output shaft 231 isreceived through a bearing 233 in an inside cover plate 221 of the leg.A top cover 247 is formed to rotatably mount both the low gear idlershaft 257 and the high gear idler shaft 263 in the dual idler landinggear leg 211. Preferably, it is not necessary to have additionalopenings in the exterior of the leg 211 through which rotating shaftsare received, and which are prime locations for leaking lubricant.

FIGS. 19 and 20 illustrates that the input shaft 227 and output shaft231 are co-axial and a reduced diameter inner end of the input shaft isreceived and borne within the output shaft. Alternately, an output shafthas a reduced diameter end portion which is received in an axial openingin the input shaft (not shown). The bearing 229 supporting the inputshaft 227 in the outside cover plate 219 permits the input shaft to bothrotate and move axially relative to the bearing. As to axial movement, aball and spring mechanism (not shown) is provided to engage the bearing229 to releasably lock the input shaft 227 in two axial positions,corresponding to high gear and low gear, respectively. The subassembly232 is shown in the high gear position in FIG. 19 and in the low gearposition in FIG. 20.

It is noted that a pinion gear 237 is formed as one piece with the inputshaft 227 and an output gear 235 is formed as one piece with the outputshaft 231. It will be appreciated that the pinion gear 237 and outputgear 235 may be formed separately from their respective shafts (227,231). The pinion gear 237 contains a first set of teeth 238 and a secondset of teeth 240. A large diameter input gear 239 is somewhat smallerthan the large diameter gear 39 of the first embodiment and is entirelyplanar, but is similarly mounted for free rotation on the input shaft227 except when engaged by the first set of teeth 238 of the pinion gear237. The output gear 235 differs from the single idler output gearconfiguration by having a third, small diameter gear member 244. Morespecifically, the dual idler landing gear leg includes a low gear idlershaft 257 including a large diameter first gear 259 engageable by thepinion gear 237 for driving the rotation of the low gear idler shaft,and a second small diameter gear 261 permanently meshed with the firstgear member 241 of the output gear 235. A separate high gear idler shaft263 includes a first high gear idler gear 265 permanently meshed withthe large diameter input gear 239, and a second high gear idler gear 267permanently meshed with the third gear member 244 of the output gear235. Accordingly, it is not necessary to balance speed in high gearagainst torque in low gear. The separate, dedicated idler shafts 257,263 decouple these design features.

As shown in FIG. 21, the axis A1 of the low gear idler shaft 257 and theaxis A2 of the high gear idler shaft 263 are offset on opposite sides ofa vertical plane P including the common axis of rotation A3 of the inputand output shafts 227, 231. Preferably, the offset is as small asnecessary to permit the gears of both idler shafts 257, 263 to mesh withthe coaxially arranged gears (235, 237, 239) of the input and outputshafts 227, 231.

The operation of the dual idler landing gear leg 211 is similar to theoperation of the embodiment of the single idler landing gear 11 shown inFIG. 5, except that different idler shafts 257, 263 are used for low andhigh gear. In high gear, the first set of teeth 238 of the pinion gear237 is partially received in the large diameter input gear 239 so thatthe large diameter gear rotates conjointly with the input shaft 227(FIG. 19). It will be appreciated that the high gear idler shaft 263rotates faster than the input shaft 227. For example, with 19 teeth onthe large diameter input gear 239 and 9 teeth on the high gear idlergear 265, the idler shaft 263 rotates 2.11 times as fast as the inputshaft 227. The rotational speed is again increased by the second highgear idler gear 267 meshed with the third gear member 244 of the outputgear. The low gear idler shaft 257 turns but does not transfer anytorque in this configuration. For low speed, high torque operation theinput shaft 227 is moved axially to the left so that the large diameterinput gear 239 is disengaged and the second set of teeth 240 on theother end of the pinion gear 237 mesh with the first low gear idler gear259 (FIG. 20). The input shaft torque is now transferred by the low gearidler shaft 257 to the output gear by way of the second low gear idlergear 261 and the first gear member 241 of the output gear 235. Asubstantial reduction is achieved both from the input shaft 227 to thelow gear idler shaft 257 and from the low gear idler shaft to the outputgear 235 by virtue of the relative sides of the meshed gears.

Preferably, the numerical values given in the range have units of turnsof the crank per inch of travel of the leg are between 1.02 and 4.5 inhigh gear and 26 and 44 in low gear. However, one skilled in the artwill understand that any combination of low and high ratios is possible.Preferably, the dual idler leg 211 provides good lift in low gear (e.g.,35 turns per inch), and an option for high gear. For example, the highgear could be either 1.02 or 4.5, with minimal change of gears and othercomponents necessary to provide the desired high gear ratio.

As set forth above with respect to the single idler embodiment, the topcover 247 is preferably made of a polymeric material such as nylon.However, it may be made of other suitable materials, such as a ductileiron casting or aluminum casting, without departing from the scope ofthe present invention. It is believed no separate bearings will benecessary if the top cover 247 is made of nylon or a like material. Theinput and output shafts 227, 231 are also supported by the top cover 247in a first yoke 269 depending from the top cover. A second yoke 271 isprovided for supporting one end of the low gear idler shaft 257 and athird yoke 273 is provided to support one end of the high gear idlershaft 263. FIGS. 24 and 25 illustrate the top cover 247 of the doubleidler landing gear leg 211 which mounts the idler shafts 257, 263 forrotation. It may be seen that each yoke 269, 271, 273 (broadly, “bearingmember”) includes a respective removable lower portion 269A, 271A, 273Awhich is attached to an upper portion 269B, 271B, 273B by a respectivepair of bolts. It is also envisioned that the top cover 247 and yokes269, 271, 273 may be made as a single, unitary piece. In that event, theidler shafts 257, 263 would be made in two pieces (not shown) to permittheir insertion into holes in the yokes 269, 271, 273. After insertionthe two pieces of the idler shaft would be connected together. In theillustrated embodiments, the first yoke 269 has three holes, including afirst hole 275A which receives the output shaft 231, a second hole 275Bwhich receives the low gear idler shaft 257 and a third hole 275C whichreceives the high gear idler shaft 263. The second yoke 271 has a singlehole 277 for another portion of the low gear idler shaft 257 and thethird yoke 273 similarly has a single hole 279 for receiving anotherportion of the high gear idler shaft 263. The output shaft 231 isreceived in the first hole 275A of the first yoke 269 and issupportingly engaged by the first yoke.

To place the idler shafts 257, 263 in the first, second and third yokes(269, 271, 273), the lower portions (269A, 271A, 273A) of the yokes areremoved, opening up the second and third holes 275B, 275C of the firstyoke and the holes 277, 279 of the second and third yokes. The low gearidler shaft 257 is placed on the top cover 247 (which is preferablyinverted for assembly) so that a section of the shaft adjacent to thefirst low gear idler gear 259 is received in the exposed portion of thesecond hole 275B of the upper portion 269B of the first yoke 269 stillassociated with the top cover. At the same time, a section of the lowgear idler shaft 257 nearer the second low gear idler gear 261 isreceived in the portion of the hole 277 in the upper portion 271A of thesecond yoke 271 which is still associated with the top cover 247.Similarly, the high gear idler shaft 263 is placed so that a section ofthe shaft adjacent to the first high gear idler gear 265 is received inthe exposed portion of the hole 279 of the upper portion of the thirdyoke 273 still associated with the top cover 247. At the same time, asection of the high gear idler shaft 263 nearer the second high gearidler gear 267 is received in the exposed portion of the third hole 275Cin the upper portion 269B of the first yoke 269.

The idler shafts 257, 263 are secured in place by bolting the lowerportions 269A, 271A, 273A to the respective upper portions 269B, 271B,273B, thereby encircling the idler shaft sections. In this way, theidler shafts 257, 263 are mounted entirely by the top cover 247. Theoutside cover plate 219 may be preassembled with the input shaft 227 andthe inside cover plate 221 may likewise be preassembled with the outputshaft 231. The input and output shafts (and associated cover plates) canbe brought together with the top cover 247 as shown in FIG. 18. Theoutput shaft 231 is received through the first hole 275A in the firstyoke 269 and the reduced diameter portion of the input shaft 227 isinserted into the output shaft. Bolts are passed through the coverplates 219, 221 and into the top cover 247. This completes thesubassembly 232 which includes all of the gearing of the landing gearleg 211 except for the bevel gear 225 attached to the top of the leadscrew (not shown but essentially the same as the screw 23 of FIG. 5). Itis further contemplated that the single idler leg 11 may use a top coversubstantially similar to the top cover 247 used by the dual idler leg211 and leave one of the yokes 271, 273 unused, as described below. Thesubassembly 232 so formed may be dropped into the open top of the leg211 in manufacture. The cover plates 219, 221 are secured to the leg 211to assemble the subassembly 232 with the upper section 215 of the leg.

FIGS. 26 and 27 illustrate another version of the single idler landinggear leg 211′ that uses a top cover 247′ having yokes 269′, 271′ and273′ substantially identical to the top cover described above withrespect to the dual idler landing gear leg 211. Thus, the same top coverand leg sections can be used to manufacture both single and dual idlerlanding gear legs. In the version illustrated in FIGS. 27 and 28, theinput and output shafts 227′, 231′ are also supported by the top cover247′ in the first yoke 269′ depending from the top cover. Either thesecond yoke 271′ or the third yoke 273′ receives and supports the idlershaft 245′. The other yoke 273′ or 271′ is not used by the subassembly232′. The operation of this version would be substantially similar tothe operation of the single idler leg 11 described above. With thisversion, both a single idler subassembly 232′ and the dual idlersubassembly 232 would use a common top cover to facilitate manufacture.

When introducing elements of the present invention or the preferredembodiment(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained. Asvarious changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

1. Landing gear for selectively supporting a semitrailer, the landinggear comprising: a leg having an upper section and a lower section intelescoping arrangement with each other; a lead screw mounted forextending and retracting the upper and lower sections relative to eachother upon rotation of the lead screw; an input shaft for applying atorque to the lead screw to drive rotation thereof, the input shaftbeing rotatable about a first rotation axis and movable in translationalong the first rotation axis for shifting between a first position forlow gear operation and a second position for high gear operation; anoutput shaft including an output gear for transmitting torque to thelead screw, the output shaft being mounted for rotation about a secondrotation axis and being generally axially aligned with the input shaft;and a gearing subassembly configured so that for each rotation of theinput shaft, the output shaft rotates less than one rotation for lowgear operation and interconnecting the generally axially aligned inputand output shafts in the second position so that for each rotation ofthe input shaft, the output shaft rotates more than one rotation wherebythe gearing subassembly augments lift when the input shaft is in thefirst position and augments speed in the second position, wherein thegearing subassembly comprises at least three gears mounted for rotationabout axes spaced from the axis of rotation of the input and outputshafts, a first of the three gears being in driving engagement with theinput shaft in the first position thereof, a second of the three gearsbeing in driving engagement with the input shaft in the second positionthereof, and a third of the three gears engaged with the output shaft,the first gear has a larger diameter than the second gear, and whereinthe gearing subassembly further comprises an idler shaft, the first,second and third gears being mounted for conjoint rotation on the idlershaft.
 2. Landing gear for selectively supporting a semitrailer, thelanding gear comprising: a leg having an upper section and a lowersection in telescoping arrangement with each other; a lead screw mountedfor extending and retracting the upper and lower sections relative toeach other upon rotation of the lead screw; an input shaft for applyinga torque to the lead screw to drive rotation thereof, the input shaftbeing rotatable about a first rotation axis and movable in translationalong the first rotation axis for shifting between a first position forlow gear operation and a second position for high gear operation; anoutput shaft including an output gear for transmitting torque to thelead screw, the output shaft being mounted for rotation about a secondrotation axis and being generally axially aligned with the input shaft;and a gearing subassembly configured so that for each rotation of theinput shaft, the output shaft rotates less than one rotation for lowgear operation and interconnecting the generally axially aligned inputand output shafts in the second position so that for each rotation ofthe input shaft, the output shaft rotates more than one rotation wherebythe gearing subassembly augments lift when the input shaft is in thefirst position and augments speed in the second position, wherein thegearing subassembly comprises at least three gears mounted for rotationabout axes spaced from the axis of rotation of the input and outputshafts, a first of the three gears being in driving engagement with theinput shaft in the first position thereof, a second of the three gearsbeing in driving engagement with the input shaft in the second positionthereof, and a third of the three gears engaged with the output shaft,the first gear has a larger diameter than the second gear, and whereinthe first and third gears rotate conjointly about a common axis. 3.Landing gear as set forth in claim 2 wherein the gearing subassemblyfurther comprises a fourth gear engaged with the output shaft. 4.Landing gear as set forth in claim 3 wherein the gearing subassemblycomprises first and second idler shafts, the first and third gears beingmounted on the first idler shaft and the second and fourth idler gearsbeing mounted on the second idler shaft.
 5. Landing gear as set forth inclaim 4 wherein the output gear includes a first gear portion meshedwith the third gear and a second gear portion meshed with the fourthgear.
 6. Landing gear as set forth in claim 5 wherein the first gearportion of the output gear has a larger diameter than the second gearportion.
 7. Landing gear for selectively supporting a semitrailer, thelanding gear comprising: a leg having an upper section and a lowersection in telescoping arrangement with each other; a lead screw mountedfor extending and retracting the upper and lower sections relative toeach other upon rotation of the lead screw; an input shaft for applyinga torque to the lead screw to drive rotation thereof, the input shaftbeing rotatable about a first rotation axis and movable in translationalong the first rotation axis for shifting between a first position forlow gear operation and a second position for high gear operation; anoutput shaft including an output gear for transmitting torque to thelead screw, the output shaft being mounted for rotation about a secondrotation axis and being generally axially aligned with the input shaft;a gearing subassembly configured so that for each rotation of the inputshaft, the output shaft rotates less than one rotation for low gearoperation and interconnecting the generally axially aligned input andoutput shafts in the second position so that for each rotation of theinput shaft, the output shaft rotates more than one rotation whereby thegearing subassembly augments lift when the input shaft is in the firstposition and augments speed in the second position, and wherein thegearing subassembly is located substantially within the upper section ofthe leg; and a top cover received within an open upper end of the uppersection of the leg and closing the open upper end, wherein the gearingsubassembly is supported by the top cover.
 8. Landing gear forselectively supporting a semitrailer, the landing gear comprising: a leghaving an upper section and a lower section in telescoping arrangementwith each other, wherein the upper section comprises opposing walls,each wall having a slot therein; a lead screw mounted for extending andretracting the upper and lower sections relative to each other uponrotation of the lead screw; an input shaft for applying a torque to thelead screw to drive rotation thereof, the input shaft being rotatableabout a first rotation axis and movable in translation along the firstrotation axis for shifting between a first position for low gearoperation and a second position for high gear operation, and wherein theinput shaft extends into the upper section of the leg through one ofsaid slots; an output shaft including an output gear for transmittingtorque to the lead screw, the output shaft being mounted for rotationabout a second rotation axis and being generally axially aligned withthe input shaft; a gearing subassembly configured so that for eachrotation of the input shaft, the output shaft rotates less than onerotation for low gear operation and interconnecting the generallyaxially aligned input and output shafts in the second position so thatfor each rotation of the input shaft, the output shaft rotates more thanone rotation whereby the gearing subassembly augments lift when theinput shaft is in the first position and augments speed in the secondposition; and a cover plate attached to the upper section generally overthe slot, the cover plate including a bearing receiving the input shaftthere through.
 9. Landing gear for selectively supporting a semitrailer,the landing gear comprising: a leg having an upper section and a lowersection in telescoping arrangement with each other, a lead screw mountedfor extending and retracting the upper and lower sections relative toeach other upon rotation of the lead screw; an input shaft rotatableabout a first rotation axis; an output shaft rotatable about a secondrotation axis and connected for driving rotation of the lead screw; anidler shaft rotatable about a third rotation axis gearing associatedwith the input shaft, output shaft, idler gear and lead screw foroperatively connecting input shaft to the lead screw for drivingrotation thereof; a bearing member located within the upper section ofthe leg and a bearing element bearing the idler shaft for rotation, thebearing member being supported by the upper section at a location abovethe location of the bearing element; and a top cover received in an openupper end of the upper section of the leg and closing the open upperend, the bearing member being supported by the top cover.
 10. Landinggear as set forth in claim 9 wherein the top cover supports a firstbearing member bearing the input and output shafts, wherein a verticalplane P includes the first rotation axis and the second rotation axis,the top cover further supporting a second bearing member bearing theidler shaft such that the third rotation axis of is offset on one sideof the vertical plane P.
 11. Landing gear as set forth in claim 10wherein the top cover further supports a third bearing member positionedon an opposite side of plane P as the second bearing member, wherein thetop cover can support the idler shaft in either the second or thirdbearing member.
 12. Landing gear as set forth in claim 9 wherein the topcover and bearing member are at least partially formed as one piece. 13.Landing gear as set forth in claim 12 wherein the top cover and bearingmember are made of polymeric material.
 14. Landing gear as set forth inclaim 9 wherein the bearing member constitutes a first bearing member,the landing gear further comprising a second bearing member locatedwithin the upper section of the leg and including a bearing elementbearing the output shaft for rotation, the bearing member beingsupported by the top cover.
 15. Landing gear as set forth in claim 14wherein the bearing member further requires a third bearing memberlocated within the upper section of the leg and including a bearingelement bearing the output shaft for rotation.
 16. Landing gear forselectively supporting a semitrailer, the landing gear comprising: a leghaving an upper section and a lower section in telescoping arrangementwith each other, the upper section having opposing walls; a first of thewalls having a slot therein at an upper end of the first wall; a leadscrew mounted for extending and retracting the upper and lower sectionsrelative to each other upon rotation of the lead screw; an input shaftrotatable about a first rotation axis and connected in operation to thelead screw for driving rotation thereof, the input shaft extending intothe upper section of the leg through the slot in the first wall; anoutput shaft rotatable about a second axis of rotation and an outputgear mounted on the output shaft, the output shaft extending into theupper section through a slot in a second of the walls; a cover plateattached to the upper section generally over the slot, the cover plateincluding a bearing receiving the input shaft there through; and anothercover plate attached to the upper section over the slot in the secondwall, the other cover plate including a bearing receiving the outputshaft there through.
 17. Landing gear as set forth in claim 16 furthercomprising an idler shaft adapted to interconnect the input shaft andthe output gear, the idler shaft being supported for rotation by thecover plates.
 18. Landing gear as set forth in claim 17 wherein thecover plates each have an opening for mounting the idler shaft andwherein the landing gear further comprises bushings carried by the coverplates in the opening for receiving ends of the idler shaft and closingthe openings in the cover plates.